since dirk is dave's father, roxy is rose's mother, jake is jade's father, and jane is john's mother and the fact that jade and john are siblings and so are rose and dave, does that mean that this is trying to suggest that roxy and dirk and jake and jane are canon, ship wise?

Dirk and Roxy are the parents of Rose and Dave & Jake and Jane are the parents of John and Jade. This doesn’t mean those ships are canon it just means their paradox slimes were mixed together to make their offspring.