A whole year, huh? You should be fine - last time you were at the border, your wife may not have even been pregnant yet. As you landed and applied for SINs, you are PRs of Canada now, and should have no problems with entry.
As a U.S. citizen your child should have the ability to visit Canada. Technically the child doesn’t even need a passport, just a birth certificate. You’d have to eventually apply to sponsor the child for PR though, as a new PR application under the family sponsorship class.
Note that if you already had a child born before you landed last year, then that might have been a different story. In that case you are suppose to tell IRCC before you land and they will ask for a medical for the baby and add the baby to the CoPR - but that doesn’t apply to births that happen after landing.
See also Baby born in US after soft landing - #21 by sameer
Luckily the baby hs a US citizen, if the baby required a visa then you might have been separated during this process for a quite a few good months, see Baby born after soft landing | Canada Immigration Forum.