Bike noise, creak, click, creaks, clicks, clicking, pinging sound - help

I reckon it could be what 31t®um said, a loose chainring bolt.

Take em all out, clean them and re-grease them and then tighten them to buggery

I had a similar problem to you, exhausted all other possibilities and then found out it was the chainring bolts. Only problem is that you said it was coming from the left crank arm

yes, i think you're right. i didn't actually see that suggestion from Murtle the Turtle until now, wish i had noticed it before.

i don't know if it's coming from the left crank, it's probably not, just seems to make the noise if i lean on that side, but that doesn't mean much.