Interesting: the word "paradise" derives from the Ancient Persian "para-daidos". It means "surrounded by walls" and refers to the Persian gardens. However, if I recall well, the word paradise is never used in Genesis? Theory about the snake: this is a typical myth in the style of "how did the animals get their shape?". The snake is punished by having to crawl in the sand for eternity. There were two trees: the Tree of Life and the Tree of Knowledge. Unfortunately, Eve ate from the wrong one, so we are still mortal, but we have a lot of knowledge.