I already made some sprites and tracks like a week ago, can i use them for this jam?

I bet, I think I saw some game jams who would allow assets made from other games, I am not entirely sure, but I think you would be able to use your own assets. :)

Trying to not sound rude, you should see the video on the jam's page first. It says that all assets (code, art and sound) must be made in the time the jam happens.

according to the video on BTP's channel, everything must be created in the one week period of the jam, so no