I was thinking about using some old ps2 games songs on my game and i wonder if that falls under the argument that im using assets that are not mine and therefore dont contributing so much for my score in the Jam, or if that is just prohibited

Have a look at https://opengameart.org - you might find something similar to what you're after. Make sure to check the licensing though, some works require credit, some are not available for commercial use etc.