When Jesus chose to go to Jerusalem, He knew He was going to die and be resurrected.

He had already told His disciples 3 times.
Matt.16:21, 17:22-23, 20:18-19

Jews had celebrated Passover each year for ~1500 years, yet didn’t recognize their Messiah.

Some people blame the Jews. Who killed Jesus?
We all did.  Rom.3:23-26; 1 Cor.15:21-22

God’s plan: Christ died for all sins. 1 John 2:2;
John 1:29,11:50-52; Isa.53:5-10; Rev.5:9,13:8
 
When Israel left Egypt with Moses, they began observing feasts to the Lord every year.

Since the time of the Exodus 1446 BC, Passover was the 1st feast celebrated each year by Israel.

Just before the Exodus, God changed the 1st month of the year to be Nisan (Abib). Exo.12:2

Hebrew months are 30 days long, starting on the new moon. That’s why Easter shifts around.

Hebrew days begin at 6 pm sunset (moonrise) - time was measured using the moon, not the sun.