A Gaza ceasefire did get some discussion. Sanders and AOC, both high profile speakers, promoted a Gaza ceasefire in their speeches. But Americans aren't interested enough in Gaza to justify a speaker who will mainly or exclusively be discussing that topic.
And yes, Americans are more interested in rescuing hostages than helping war victims. Not just in the abstract, polling consistently shows that Americans overwhelmingly view Hamas as evil but are more evenly divided regarding Netanyahu. It might seem unfair, but don't blame the DNC. That's our national mood, which the DNC will respond to. If Gaza activists want that to change then they will have to do more work.
Who said change is easy? Those who challenge entrenched interests will always have a difficult road ahead.
But it's not impossible. Civil rights activists achieved change, LGBTQ activists achieved change, even wack-job anti-abortion activists achieved change. So can Gaza activists.