My understanding that there have always been thousands of different “cold” viruses, so one cannot be immune to all of them. They just all cause similar reactions so are called the same thing generically. Same with influenza. But the chance of one suffering from the very same species (if you will) is almost nil after having had it.
There are only four deadly strains of Ebola, unless more show up. One would think that yes, a survivor would become immune. However earlier in the thread other people posted examples of other viral diseases that are never really fully treated, just suppressed. A poster above said that he got shingles twice - and it's caused by a virus. As this very article suggests, doctors themselves are not sure if Ebola can reinfect the patient after he is cured. Maybe all that it takes is one flight in an airplane at 30 thousand feet, one highly energetic (gamma) photon that hits the DNA molecule of a dormant virus and messes it up... and now the virus is back in business.
Common knowledge that colds become fewer and milder as you get older — this I believe is due to immunity acquired earlier in life to individual rhinoviruses and partial immunity to very similar ones. Not sure if coronavirus and enterovirus colds do the same thing..