The rishis belonged to an elite class of male and female holy persons said to have received the Vedas through revelation. They “heard” and then passed on the sacred Vedas in the form of hymns.
Through song and oral repetition the Vedas were transmitted to disciples for centuries until the verses were eventually written down.
For this reason pinpointing the age of the Vedas is problematic because (most likely) no one really knows when the Vedic revelations were received and orally composed.
Also, from a contemporary skeptics eye, no one really knows if the rishis just had good imaginations, were repeating cultural biases, or whether their songs came from God (or partly from God).
This may seem politically incorrect or indelicate to say, but it’s so common for people to level this kind of critique against Jewish and Christian scripture, it only seems fair and right that all sacred scripture should be met with the same kind of critical scrutiny.