The Spanish cara (“head”) comes from the same Latin word (cara), also meaning the same, “head.”
From that Latin, we get the English cheer (via French’s chere). Thus, the ch-r of cheer maps to the c-r of cara.
A face — after all — is the most human thing intended to make us thankful (to cheers a toast!) for life. And most faces fill us with enough happiness to make us cheerful!