No, those are not banana seedlings.
You said you got them from a store bought banana, the little black dots you see inside are
not seeds - they are seedless.
Real banana seeds are found from 'wild' type bananas and are considered inedible because they are huge marble sized and hard as a rock.
Edible bananas like store bought ones can only be grown from a pup/sucker off another banana plant or grown from a tissue culture of the rhizome - they cannot be grown from seed as they do not contain real seeds. You can buy them at a local nursery or online on sites like Ebay or even from members on this forum.
Here is a picture of what real banana seeds look like
