Sparta and Carthage had elected governments. Hell, Imperial Rome had electeds. Elections are a prerequisite for democracy, not a proof of one.
Universal suffrage is an ideal entirely reliant on how the denominator is defined. Delineating the polity (i.e., polis) is an institution in democratic exercise--we traditionally punt this question to that of citizenship.
(On the opposite, you have countries where you can vote in local elections even if you do NOT have citizenship.)
Of course we do. Because it’s convention. But not everyone within a border geometry is a citizen. And why a border geometry is what it is usually relies on other questions.