What to do with 15 week old baby?

Looking for ideas.. I feel like we're at a stage where she wants entertainment but she's still too little to enjoy many things. Lately she's just been voraciously sucking on her hands and even if I try with some toys, or to put her on her tummy with things to look at, she's still mostly interested in just sucking her fingers. Nothing wrong with sucking fingers and I know it's an important milestone for weaning when the time comes, but I feel like maybe she's bored and I'm not doing enough to make her happy and engaged? She starts yawning early in her wake window.

She also rolled once from her tummy to her back 2 weeks ago but has never done that again since.