If it's callisa, it should grow pretty fast and reveal itself.
If it's a variagated pup from those other plants, I'd think it would grow quite slow! Could be wrong...
I just don't see it being a seedling of any sort, that's just doesn't look like seedling growth to me, too big, too robust, no sign of cotyledons or seed leaves or any of that.
I think I see a stem between the 2 sets of leaves, would a pineapple lily( eucomis?) or blood lily (scadaxus/heamanthis?) have leaves arranged opposite, and have a length of stem between more sets of leaves?
I've only grown a few of each, and only from blooming size bulbs I bought, and eventually killed...
Never a seedling though, so maybe if one of these plants looks different as a seedling than as a mature plant, I don't know, but in my experience, both those plants grow leaves from an underground bulb, with no stem until the bloom.
So I think that's going to rule those out.
Would be awesome if it was a canna, that's what I'm pulling for!
I'm leaning more towards the callisa, or a similar one, I've only grown the plain C. Fragans, and I don't have them anymore, they got a little troublesome, hopping from pot to pot and growing and shoots laterals out... Some even got "sick" and I trashed them.
Other than people, birds are the other great spreader of plants, we might move more plants around now, but for millions of years...
I could easily see a bird gathering some up for nests, or whatever they're up to...