>>528455883
Well, for reference, this is the spritesheet for the final boss from Kirby's Adventure. I'd say he's overall more complex looking than the deltarune one.
But, Kirby's adventure didn't take as long as deltarune. Yes I have to admit, they had a team of japanese men whose sole life purpose was to make it and get paid for it, but also this was before we had the incredibly efficient, ergonomic easy to use tools and technologies we have nowadays.
https://en.wikipedia.org/wiki/Kirby's_Dream_Land#Development
For the first kirby game, this part describes how inefficient they were aswell.
By the way, I am biased. And my bias is that I have the opinion that modern developers are lazy and weak.