Like it or not, house races are becoming nationalized.
For the republicans, this is easy, because they have an iron-clad ideology and propaganda machine that has just-short-of-radicalized 30% of the electorate and has smoothed over any internal squabbling by becoming so singular in their list of policy prescriptions & identities.
The democrats are incredibly pluralistic/cosmopolitan by comparison, and are largely defined by the set of people who've opted out or were left out by the GOP's maniacal focus. This means that what worked for the GOP (purity tests, intense loyalty, and leaning into the nationalization of every race) are actually destablizing the democratic party.
Before Reagan, the GOP was actually more of the "big tent" party with competing ideologies and constituencies, and the way they handled it then was to begrudgingly support the McCarthyite & Rockefeller wings during elections and then battle things out during governance. The democrats, meanwhile, are spilling most of their blood in primaries and election run-up navel gazing ("Maybe I'd vote for her if she had a positive message" nonsense). That moral high ground might result in a bunch of liberal individuals with a clean conscience, but the broader effect is that Republicans win.
All told, we don't have much control who's in the DNC/DCC leadership or which candidates they field. It's clear that progressives did a bunch of damage to Ossoff by simply complaining about him, to no productive effect. The only sensible path forward in a first-past-the-post system like ours is to vote brainlessly for whatever D is on the ticket in hopes of eventually unseating the Republican lock on the house and state legislatures prior to the 2020 redistricting.
