Can confirm, I myself was a one person support desk (for a restaurant chain) and just never officially had a title. The internal moniker of "the IT guru" was fine for an email signature, but certainly not for a resume. (I've since made other retroactive edits to that, both for something more sensible and to better represent years of scope creep.)

Startups are weird though, new college grads can be (inexperienced) CTOs & CEOs if they start a company together