Jose Quintana’s long-awaited Mets debut went well after a shaky first two innings, leaving manager Buck Showalter to say the left-hander “is gonna help us.”

That may be true.

Quintana was solid over five innings Thursday, allowing a pair of runs, in his first start since surgery this spring to repair a stress fracture in his rib.

But his solid outing came in another Mets loss, this one a 6-2 defeat to the awful White Sox at Citi Field that snapped a three-game winning streak.

With the Aug. 1 trade deadline fast approaching, it’s unclear how much time the Mets have to prove they are capable of making a run at the playoffs, so Quintana may not be able to do much to get them there if the front office and ownership decide to pull the plug on the season.

Quintana, who signed a two-year, $26 million deal with the Mets this past offseason, is among those who still believe the team can get to the playoffs, though the Mets dropped back to six games under .500 (45-51) and face a five-game road trip to Boston and The Bronx.

Asked if he still thought the Mets were capable of making the playoffs, Quintana didn’t hesitate.

“For sure, no doubt,’’ Quintana said after the Mets took two of three from the White Sox. “We have a long time ahead. The way we played this series, really good things are gonna happen.

“We’ll keep fighting and you never know what’s gonna happen. The second half [of the season], we started off good.”

That may not be enough for a team that hasn’t seen the .500 mark since early June.

But one of the main issues has been subpar starting pitching and some important arms have shown promising signs of late, from Max Scherzer and Justin Verlander making good starts to Quintana throwing three scoreless innings after allowing a run in each of his first two on Thursday.

Quintana said he “felt great out there. I was excited to make my debut at home and every inning felt better and better.”

The lefty pointed to improved command as the start went.

Showalter noted that Quintana’s rough opening inning was marred by a pair of soft-contact hits that cost him.

With Tim Anderson on first base and one out, Luis Robert Jr. hit a 68-mph bloop to left that sent Anderson to third and Eloy Jimenez followed with a 77 mph single to center that scored Anderson for the game’s first run.

“He had those two flares in the first, but that’s baseball,” Showalter said.

It was the 34-year-old’s first game since he pitched in the wild-card series in October with the Cardinals.

He acknowledged he had to adjust a bit to the pitch clock, which he’d only dealt with in the spring and during minor league rehab games.

“He showed all the things he’s good at: command of the fastball and attacking hitters,” Showalter said of Quintana, whose velocity was slightly down from previous seasons.

Still, scouts were impressed with his effectiveness and efficiency, with no walks before he was replaced by Drew Smith to start the sixth after 77 pitches (Showalter said he didn’t want Quintana to get near the 90-pitch mark), with the Mets down 2-1.

Smith faltered and allowed four runs in the sixth, hurt also by a Pete Alonso error that led to three unearned runs.