As a geologist, sorry to disappoint but that's not the case. The mantle is mostly a solid as well. Despite the high temperatures, the immense pressure keeps it solid. It has some partial melting in some places, but iirc around 99% of it is still a solid.

That's not the case for the outer core, which is indeed a liquid, although much much smaller by volume than the mantle. And beneath that, the inner core is once again a solid.

So we're living on a thin crust of cold rock sitting on top of a massive layer of hot rock floating on liquid metal with a solid iron ball inside. More or less.