Yes, naturally it would be easier to not use premade assets and just use whatever's available in your engine. It would also be easier to spend a month on the game instead of 48 hours, and it would be easier to not bother with the theme and just make whatever game you want.
The Kenney Jam is meant to be a fun challenge for yourself. The fun and challenge comes from the limitations given, one of those limitations being that you can only use premade game assets made by Kenney or me. If you're looking to circumvent this limitation then you're missing the point of the jam and this might not be the jam for you.