Neither profile is PPP, so you should not have been blocked from making the connection. The https://www.wikitree.com/wiki/Van_Couwenhoven-39 profile for the the father of https://www.wikitree.com/wiki/VanCouwenhoven-23 is PPP, but that should not prevent what you are trying to do. If it did, there may be a bug needing to be reported.
Regardless of that, it is worthwhile to discuss these profiles. The will of Gerret Jansen does refer to a son named Jan, and the birth date on the Jan Gerretse profile is consistent with that profile being the son of a man who was born in 1676 and died in 1712, but I do not see much in the way of sources on either profile (just the wills), and the wills do not provide evidence for entire biographies. What evidence, other than the names, is there for these men being father and son? By the 1700s there were many cousins with the same names in New Netherland, and one of the few things I know about the van Couwenhovens is that they were numerous, so I would expect a potential for confusion.... Do any of them have baptism or marriage records?