There is much that can be said about Palm Sunday and much that can be said about the Feast of Booths. The “big idea” that you should see is that Palm Sunday is the fulfillment of, and perhaps recapitulation of, the Feast of Booths. We can see this by comparing a few texts.
Mark 11:8- 10
And many spread their clothes on the road, and others cut down leafy branches from the trees and spread them on the road. Then those who went before and those who followed cried out, saying:
‘ Blessed is He who comes in the name of the LORD!’
Blessed is the kingdom of our father David
That comes in the name of the Lord!
Hosanna in the highest!”
The Jews greeting Jesus are engaged in a prepared action. They have palm branches which they had cut down from trees (not exactly a spontaneous activity), and they quote a specific portion of a specific psalm. They knew what they were doing.
This was a sort of Festival of Booths. The description of this festival is found in Lev. 23:33-44. Let me point out one part of that description:
vs. 40 And you shall take for yourselves on the first day the fruit of beautiful trees, branches of palm trees, the boughs of leafy trees, and willows of the brook; and you shall rejoice before the LORD your God for seven days.
Palm branches were a liturgical element of the Feast of Booths.
The Jews quote Psalm 118: 26. The very next verse of that psalm says, “The LORD is God, and he has made his light shine upon us. With boughs in hand, join in the festal procession up to the horns of the altar.”
So the Jews, with boughs in hand, are joining in Jesus’ process, which of course, ends on the altar.