Once you have sufficient electrical power, you can heat things in other ways - for example, aluminum smelting requires even higher temperatures than steel and uses electricity https://en.wikipedia.org/wiki/Aluminium_smelting.
The title of the piece is Could we reboot a modern civilisation without fossil fuels?, and is well worth the read.
So, sure, yeah, aluminium melts at about 650 degrees (I considered this fact when looking at aluminium pizza trays for my oven, which can, though rarely does, go beyond 450) and is smelted about 150 more than that.
But in order to smelt it you of course need receptacles that won't melt at that temperature - ie, steel (plus insulation). I was off by a couple of hundred degrees in my earlier comment - steel smelting is around 1300-1500 degrees. So we're back to the original problem.
As to wind and hydro, sure, yes, you can easily generate power from those, as we did for millennia using mostly timber constructs. Though I'm not sure if you're suggesting getting electrical power from those sources is easy, absent some sophisticated technological capabilities (wire-making, for starters).