Probably not ancestrally, no. At least it likely wasn’t a major part of the diet. Domestic cats fed on largely raw fish diets have a tendencely to thiamine deficiency because of thiamine destroying enzymes in said uncooked fish. Meanwhile an excess of fish-oil heavy fish ( raw or cooked ) like tuna apparently can cause steatitis. So too much fish is bad for your cat and as such I’d say it is pretty safe to assume that it was never a major portion of our ancestral cat’s diet ( which makes sense considering the genetic origins in the Near East ).
If you dig around on the web, you’ll find a number of sites like this that advise not feeding any fish or fish-flavored foods to your cat. Others are more moderate and say keep it down to maybe twice a week. Without necessarily fully accepting all the claims of the anti-fish crew ( I reserve judgement ) I personally don’t feed fish-based cat foods for two reasons:
1.) There is a far-as-I-know unproven link to fish and increased urolithiasis and as I’ve already had one expensive bout of struvite formation in one of my ( pretty young ) cats, I’d just as soon avoid a repeat. The reasoning seems to be based on the magnesium/phosphorus ratios in fish-based foods. While I’m unconvinced, it’s an easy enough thing to avoid.
2.) Anecdotally I think the same cat with the struvite issues may have an allergy - at least he vomited a lot on a couple of previous forays into wet fish-based foods. But then he is a bit vomity in general, so who knows. But again, easy enough to avoid.
Why they like it I’m guessing is down to the fatty oils and strong flavor. A little fish is probably fine and for an ancestral wild cat any catch was probably a good catch and they were never exposed to enough fish to develop problems. Of course some claim it is just habituation from modern fish-centric cat diets, but I don’t think I buy that.
I will say of my current two, Mr. Crystals-in-his-penis, aka Mr. Vomity, is utterly indifferent to enticements like cooked tuna. My other cat ( Mr. I’ll-try-anything ) adores tuna when offered it. My previous cat of 17 years had zero interest in fish as well. So, go figure.
I’ll just add that one site I came across argued that chicken-based diets seem to cause the fewest allergic responses AND the least kitty gas. Just a FYI that those with flatulent kitties might want to check into :p.