The theme for the jam demands need of good artwork in order to feel the story at its best. Me as a solo developer don't have much art skills to make some quality sprites for the game within the deadline, so I wanted to ask can we use open source art in our game by providing credits so that we can focus on other aspects of game properly.

Rule #1 - You can use assets but MUST list them if they are not your own.

So, yes, you can use open source art, provided you give the appropriate credit.