I suspect the more significant difference here is the selection pressures. Take a good look at any part of a bird and you'll see millions of years of selection for reduced weight. The cost of weight is just so much greater when you're flying. Interesting too that bats tend to have lower neuron counts than say rodents. Did dinosaurs have a more weight efficient brain before flight, or were they forced to shrink before re-evolving that complexity in a smaller package?

It's unclear what you're saying or how it responds to the OP and his critics.

If birds and primates today belong to equally long evolutionary lineages, then they have both had the same amount of time to adapt.

Now, speciation is what makes things interesting, because species diversify the subjects of adaptation. So, if we say some bird species has been around for longer than the human species, then you can say that that bird species has been subjected to adaptation pressures for longer (though this, too, is too simplistic; adaptation pressures are not uniformly distributed).

This, of course, starts getting into philosophical questions about the notion of "species". Modern biology has a poor grasp of what it means to be a species. The biological literature alone contains about 20 different operating definitions. To reconcile evolution with the notion of species, some have argued that all or almost all living things belong to a single species, but we're actually seeing a resurgence of functionalist/teleological notions in biology today, because it turns out you cannot explain or classify living things without such notions.

If the lineage that led to humans had fewer reproductive cycles that fit within a given time frame, then the faster reproducing animals and the animals that generated more offspring had more time to evolve because evolution is primarily driven through reproduction cycles and how many offspring you have (when there’s selection pressure). There’s epigentics to tweak things but the major driver is still a full reproductive generation. It’s obviously more complicated than such a simple model (eg crocodiles and sharks have been largely unchanged for a long time) but it’s a good rough first order approximation that satisfies the original statement. It’s more interesting to take a stronger intent of the author than nitpicking them being technically wrong with the idea they expressed.

Sure. But the "if" is doing a lot of lifting. In other words, it is an a posterior empirical question, not an a prior logical necessity.

I don’t think so considering mammals in general have longer lifespans than birds and primates specifically have very long lifespans

Most of our mammal ancestors between us and dinosaur times had likely had extremely short lifespans as well, often shorter than the ancestors of modern songbirds.

> This means that for a given unit of time, shorter reproduction cycles and more offspring results in faster adaptation which is what OP meant and what the unhelpful pedantry doesn’t describe.

There's no indication that this is what the OP meant. If the OP meant that, they'd be saying that birds evolved faster, not that they had an ancestor that evolved a very long time ago, which is a meaningless statement.

I agree one should interpret what people say charitably, but there's a difference between that and just pretending that someone made a totally different claim in order to make a nonsense statement seem less silly.

Of course, it gets more complicated when you also consider susceptibility to mutations.