"Stacked" leaves or closely sited leaf nodes are typically a characteristic of dwarf cultivars of Japanese maples. You may have got something rather special with this seedling :-))

Wow! cool tree! you're lucky to get that. It's looks a bit like a young Acer Palmatum 'Kurenai Jishi'.

Thank you for the good news!

We have one large Japanese maple, about 30-40 years old - that this must have come from. I am amazed at the variety of seedlings we get. Most have the typical shaped leaf, as here, but some are longer with slimmer lobes, some have 7 lobes that have serrated edges, we have a couple of bright green ones, not a hint of red. I also found one that is yellow in the center of the leaves, blending into red at the edges. I haven’t seen any other JPs nearby, so I assume all these seedlings come from the same tree?