For an interesting and extensively researched book about the historical Jesus, I highly recommend reading Zealot, by Reza Aslan. Besides the life of Jesus, the author delves into the disagreements between his early followers right after his death, primarily between James (Jesus' brother) and Paul. He makes the argument that it was Paul who turned Jesus into a divine figure.
https://www.amazon.com/ZEALOT-Life-Times-Jesus-Nazareth/dp/140006922X
It's a fun read.