This is kind of like if you're walking through the woods and you discover piles of bear shit as you go. The bear shit implies there's at least one bear in the woods, but it does not preclude that there could be multiple bears responsible for it.
The Higgs field is a solution to the question of why some fundamental particles have mass. Theoretically, such a field is well-motivated. If such a field exists, it implies there is at least one massive, spin-zero particle that we have decided to call the Higgs boson. There are various extensions to our models, such as the so-called "Higgs two-doublet model" which SUSY extends, where more than one Higgs exists.