It's a fig! Exact leaf shape and texture don't conform to any standard and are quite variable, especially with seedlings. I've seen that much variation on a single plant. The side views clinched it for me, since the stem, the petioles, and the new bud all have the fig gestalt. The major difference between fig and mulberry is size: fig has bigger, thicker growth all around. New mulberry leaves have two upward pointing bracts where the petiole connects to the stem.

Thanks Jeb I thought it might be :)

Yup, agreed on the ID. You could probably take cuttings a few nodes long & pot them back into mother plant's pot, to make it look even more full & lush.

Likely Oenothera biennis. If you look around there are probably some first year non flowering rosettes.