Why isn’t there a vaccine for the common cold?

Why isn’t there a vaccine for the common cold? For the same reason there won’t be a vaccine for the COVID-19 virus. Any attempt to weaken these small retro viruses to create a vaccine mutates the virus into another strain. According to the news there are at least 13 attempts to create a vaccine for the COVID-19 virus. Meaning that they’ve created 13 new strains of the virus.