Can't download sketches via USB-serial converter onto 644P, even with a bootloader

Thanks for sticking around tho, I really appreciate your efforts in trying to work out the problem. It's crazy cuz in this case the issue couldn't be found in the schematic and can very easily be glanced over. On hindsight, I can read 8mhz on the crystal in my photo! Insane. Oh, and my Rx/tx LEDs work perfectly now. Everything works as I intended. Phew.