What, not even pinewood and gelatin for ribs and stringers, and some linen cloth plus pine resin and alcohol for doping? Seriously, that's like 1000BC tech lev

What, not even pinewood and gelatin for ribs and stringers, and some linen cloth plus pine resin and alcohol for doping? Seriously, that's like 1000BC tech level. Wing is no problem as long as one can calculate how to make it stiff enough and of a right shape.