... but those don't have the spike protein that CoVID has.
What does that mean? Do they not have similarly unique antigens?
CoVID-19 is a much more dangerous disease than other coronaviruses because it has a spike protein that binds to the ACE-2 receptor on your kidney, heart, blood vessel, and yes lung cells. Other coronaviruses have different spike proteins that bind to different receptors and don't seem to kill people effectively as the CoVID-19 spike protein.
CoVID neutralizing antibodies target the unique spike protein so the fact that other coronaviruses don't present a durable target isn't relevant.