“All spoken languages are equally old” but then in the next point: Welsh is older than English. You must have miscommunicated here? Obviously all spoken languages are not “equally old”…
are humans older than chimps?
no, we share a common ancestor.
Have chimps been in x country for longer than humans? maybe
not the same question
Older = spoken earlier. A direct ancestor of Welsh was spoken earlier than a direct ancestor of English in Great Britain, but as both languages are direct descendants of Proto-Indo-European, they are equally old somewhere.
But there's an added wrinkle of which language (either spoken or written) stays mutually intelligible with the current variant for the furthest amount of time back. And tons of languages exist that are Creoles and formed from pidgins and essentially came into existence during the recent colonial era. And events like the massive flood of French vocab into English create some discontinuities in intelligibility over time. Evolution of any sort tends to not be a smooth linear process