That’s how brain works. It connects things, and comes up with new things.
If you know a lot, it’s hard to see anything creative or novel.
If you experience or read a lot on a topic, there’s a good chance that you can come up with a logical next step. You may feel creative because you cannot understand how you came up with the next step (when you don’t remember its source), or you may find it obvious because you keep a complete record of what you read or think. This may also justify why we think all the important inventions have happened in the past, when many studies and experiences were not recorded properly or communicated widely.