That business about the Jews killing Jesus doesn’t sit well with me either. He was condemned under Roman law, by a Roman authority. However, I’m not so sure about the Jews using his blood as protection or some sort of blessing. I would think they’d have to see him as someone or something of importance, which I don’t think they did. I think the “let his blood be upon us” is more of a “yeah ok whatever, just get this over with”. After all, that crowd wasn’t his followers, but probably people who didn’t want to **** off Pilate any more. I think this story is open to many interpretations, allowing people to take away what strikes them. I’m not comfortable with coincidences, I think there are things at work we don’t at times understand.
No.....the lamb's blood was definitely not to symbolize the blood of Jesus, and it definitely had nothing at all to do with Jesus or his crucifixion. Passover happened long before the life of Jesus.
Proof:
Passover started when Moses threatened the Egyptian pharaoh in
Passover Fast Facts | CNN
The link above says that Moses's exodus (from Egypt) was circa 1200's BC (long before the life of Jesus Christ).
Passover in the Hebrew Bible
The website, above, says that the celebration of the holiday of Passover began around the 5th century BC (which is hundreds of years after the exodus, and hundreds of years before the life of Jesus.
It was celebrated on the 14th day of Nissan (not a Japanese car).
The website also says that the Passover Papyrus from Elephantine (held at the Egyptian Museum of Berlin) doesn't mention anything about Passover except that it was celebrated. This website concludes that subsequent editors detailed eating a lamb and smearing its blood as a sign to God to "pass" "over" their house when he punishes Egyptians.
Exodus 12:9 says that Moses was commanded to roast (not boil in water) the lamb. That would mean that the old testament was written after the time of Moses.
Lacking full proof, I'd say that you are right about being open to many interpretations.