Over the years TMNT has;
* Changed Baxter Stockman from black, to white, then back to black.
* Changed April’s age from an adult to a teenager
* April has been, a news reporter, a drawing brought to life, a scientist, a high schooler with alien powers
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* Shredder has been a human, an alien, a reincarnated Japanese warrior with a dragon spirit, a literal demon, a super mutant
* Splinter has been a man to rat, a rat to man, a Japanese warrior reborn as a rat, old, young, tall, short
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* Casey has changed ages, his origins has changed, heck Hun was his DAD one time!
* The turtles have had a different look EVERY TIME! They ages have changed, their origins have changed.

Literally so much has been changed throughout the TMNT history.
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You can’t tell the same story over & over, & expect a franchise to survive! 1 of the reasons TMNT has been around for so long is because it takes a known story & tells it differently each time! It can be dark & gritty or colourful & funny!
As IDW said;
CHANGE IS CONSTANT!