A primary element in Creation is the cycle of life. The whole point of the Seven Days of Creation narrative was to mark this very thing. God wove the seven day cycle into the fabric of reality. All of our human existence, even before the Fall, consisted of cycles. After the Fall, with the insertion of mortality, it became critical to mark the cycle of the year, as well as the seven day cycle.
God even instituted a Sabbath Year observance. He makes it clear this has to do with the rhythm of how Creation works. Just as the Sabbath Day belongs to God, so does this Sabbath Year; it’s an offering in which His covenant people must trust Him to provide for them while the land can rest and recover. They would eat the wild produce instead. To carry the symbolism further, this observance is a gift to the needy, encouraging them to harvest any volunteer crops. And what they don’t use becomes a gift to the natural world. This applies to every element of cultivation.
The Lord ties this to the seven day cycle. Further, God notes a major point here is letting your household servants and animals take a break. God rested on that day, so should all Creation. This is in our best interest; it makes us consistent with reality itself. In all of these observances, no one should so much as mention the name of other gods. There is only one God, but more to the point, there was only one God Israel had to concern themselves with, and He wasn’t going to share.
Related to all of this was the cycle of feasts. Here God mentions the three big feasts:
Unleavened Bread: (7 days following Passover) 14-20 Abib (later called Nisan); late March for us
Firstfruits: (end of Unleavened Bread) 21 Abib; early April
Ingathering: (Tabernacles) 15-21 Tishri; early October
Unleavened Bread should be obvious, as it commences with Passover, the single celebration yearly that reminds Israel of their national birth and redemption. They were redeemed from slavery to become the feudal property of God as His own adopted family. It was largely symbolic to destroy all the yeast they had been keeping as sourdough during the year, so they could start with a fresh culture after this feast.
Notice the comment about not appearing before God empty-handed. This is not a reference to offerings, but to the feast they would share with God in His Presence. Nobody will leave hungry. That means if anyone is in poverty, someone will be obliged to adopt them temporarily and make sure they partake of the feast. Typically this would be one’s nearest kin. It points out how the survival of everyone under the Covenant is an obligation laid on the nation as a whole, who should be grateful for their redemption.
Firstfruits is right after the end of Unleavened Bread. It has a separate purpose, but it quickly became the practice for folks coming to the Temple for Passover/Unleavened Bread to stick around until it was all finished. Then they would go home and harvest the various crops coming ripe across the balance of spring and through the summer. In the fall, they would come back for another round of holy day observances. But Trumpets and the Day of Atonement didn’t require every man to appear, only the last observance, which was the Ingathering, AKA Tabernacles. Notice that it is the Feasts which become the most sacred in terms of mandatory attendance. The emphasis is on joyfully celebrating the goodness of their God.
By the way, for the record, the definition of “males” required to attend would exclude those too old or otherwise disabled, and included only those who were past their bar-Mitzvah. The Sons of the Covenant had to honor the Covenant. They should have been quite eager to do so, as it was all counted as a high privilege.
Never make a blood offering with leaven, said the Lord. This is unique to Israel in history. No other nation or religion had this symbol. It reminded them how they fled Egyptian slavery by God’s strong hand of deliverance. The nation marched out at dawn without time to let their bread rise and bake in the morning. The other item was ensuring that the meat didn’t have time to rot overnight. What wasn’t eaten by bedtime must be burned in the fire. It symbolizes both readiness to march at God’s command and the purity of nothing rotten, same as the business with leaven.
God restates the duty of giving Him the first of all agricultural produce. It’s a permanent debt we owe to God so long as we live on this earth. We owe our very lives to Him, so the prohibition against boiling a kid in its mother’s milk makes perfect sense. As I understand it, the kid was dropped alive in that boiling milk. It was a very common pagan fertility ritual in which one would consume a little of the resulting soupy milk, and then sprinkle it on one’s agricultural resources. This is consistent with the general prohibition against consuming anything with blood in it. God is not like other deities and won’t tolerate being treated that way. All blood is either an offering to Him, or it’s evidence of deep moral depravity that cries out against us.
As a practical point to go along with this: the red-colored liquid we find in modern unground beef isn’t blood, but a red liquid protein found in bovine (and probably other) meat. I don’t think any modern meat is sold with any blood because of health regulations, seeing as blood is a big carrier of pathogens and whatnot.
Well, in the food industry at large, the grey congealed blubbery stuff that leaks out of meat in cooking is considered blood. There’s not nearly as much there as you would get from a fresh kill that wasn’t properly drained. Most carcasses during slaughter are hung head-down at the plant to drain off as much blood as is practical. Kosher meat is mostly a matter of drained longer and more carefully. God’s Law here isn’t an absolute in physical terms; the point is reverence, not biology. You can be fussy and buy only kosher meat if it matters to your conscience, but it’s not a violation of Biblical Law to eat hamburgers or whatever, even if you see that small amount of blood in cooking.
Kosher requires the cut on a steer slice through the carotid artery, jugular vein and larynx while the animal is standing and awake then it is slowly raised to drain the blood. They are not stunned.