One of the really strange ones is the story of Balaam and his talking donkey. In this story, Balaam is on his way to do something against the will of God, and his donkey sees an angel blocking the path. The donkey refuses to move and then starts talking to Balaam, warning him about the angel. It's quite an odd concept to have a donkey be able to communicate in such a way.
In the story of Jonah. Jonah was swallowed by a large fish (or whale). It's really strange that a man could survive inside a sea creature for days. It goes against what we know about the digestive systems of such animals and the ability of a human to endure such an environment.
The transfiguration of Jesus is rather strange as well. Jesus took Peter, James, and John up a mountain, and his appearance changed. His face shone like the sun and his clothes became as white as light. Moses and Elijah also appeared. It's a very supernatural event that's not easy to fully understand, but it shows Jesus' divine nature.
One of the main themes is the relationship between God and His people. It shows how God chose the Israelites, made covenants with them, and guided them. Another theme is the concept of sin and redemption. The stories often depict the people's disobedience and God's mercy in forgiving them when they repent.
The age of the Old Testament stories is difficult to pinpoint precisely. They have been passed down and developed over a long period, likely spanning several millennia.
I'm not entirely sure specifically which '87' stories you are referring to. However, in the Old Testament, the concept of 'the beast' can be related to various symbolic or literal interpretations. For example, in the book of Daniel, there are visions of strange beasts that represent kingdoms or powers. Each beast has distinct characteristics that signify different aspects of worldly rule and its relationship with the divine.
The Exodus is a very significant event. It's when the Israelites were led out of slavery in Egypt by Moses. Another one is the creation of the world as described in the book of Genesis.