Welcome to the forum!
I just managed to get my Star Wars group to test HARP SF (been trying to play HARP SF for years!)and I'm being slightly pushy about trying HARP Fantasy too. This is a group I've played with for about a year and a half, one long FFG Star Wars RPG campaign (40 odd sessions.) They're used to d20 stuff, Vampire, easy peasy narrative squeesy games
Which is all fun and games. Literally. Heroic stuff, where you just by being an adventurer, will be considered super-human.
HARP, in my opinion, is different. It's about becoming the hero, but you don't start out as one - and you won't be close to anything like a hero (in power level at least) before lvl 10 anyway - although demeanour and actions may be considerably heroic. I'm not sure I'd say HARP is better than 5e or other games, but it's different, it caters to a different style of storytelling, a different journey. One that I prefer for both Fantasy and SF, but it is more complicated, it is more bookkeeping, it requires more involvement.
You can always get people involved, it just takes a bit of coaxing, run a few other games, lure them in with fun and games, then gently nudge them into testing HARP... then let them feel like big damn heroes with some easy encounters... then slap them down with a 2 headed hydra ... in a pool... on a starship ... almost killing half the group - silently thanking the powers that be that you managed to talk one of the players into being a considerably competent medic...
The fear in the players' eyes when they heard "dead in 12 rounds" ... they were used to nice, safe, Star Wars, where dying is only a risk if it's plot-related and more or less planned - accidental death never happened, was never even close. I think they liked the meeting with potential death - granted I had to fudge a bit the dying rules are a bit harsh, but I felt my interpretation was within the rules, if not clearly so.