In the past 15 months, baseball’s glass ceiling has been shattered with the first female general manager in MLB, the first female on-field at the major league level and the first female manager in the minors.

Kelsie Whitmore joined Marlins GM Kim Ng, Single-A Tampa manager Rachel Balkovec and Giants coach Alyssa Nakken as a pioneering woman in the game when she started in left field for the Staten Island FerryHawks of the Atlantic League on Sunday in Gastonia, N.C.

Whitmore didn’t start in the FerryHawks’ home opener Tuesday night, but she was inserted as a pinch-runner and scored her first run of the season in the eighth inning of a 4-1 win over the Lexington Legends. 

The next milestone for the 23-year-old California native will be to become the first woman to pitch in the MLB partner league. Yes, the former Cal State Fullerton softball star has designs on joining Shohei Ohtani as a double threat in the field and on the mound.

“Sunday was a great experience. At the end of the day, it’s baseball,” Whitmore told The Post before the game. “I’m definitely feeling confident and ready to go out there and compete and staying ready to pitch whenever I get that opportunity.”

Nelson Figueroa, the former Mets righty and the co-host of The Post’s “Amazin’ but True” podcast, also serves as the Staten Island pitching coach under manager Edgardo Alfonzo. He admits the coaching staff is looking for the right time for her mound debut.

“We want to give her an opportunity when we’re up by some runs to let her get her feet wet that way,” Figueroa said. “At this point, it feels like the same thing when we started her in left field. It was, ‘What do we have to lose?’ And she didn’t disappoint.

“She is relentless in her preparation, and all she’s done is continue to impress people. … She got hit by a pitch [Sunday] and ran right to first base. She’s a baseball player. She honestly has been a breath of fresh air.”

Figueroa is hoping that a mechanical adjustment eventually will boost the 5-foot-6 Whitmore’s fastball velocity from around 78-79 miles per hour into the 80s, but he believes the “natural movement” on Whitmore’s four pitches will help her avoid hard contact when hitters are so used to seeing upper-90s heat.

“That’s the thing that our guys facing her were very surprised about. I think it takes you about three seconds to get over the fact that she’s a woman,” Figueroa said. “She actually can put the ball where she wants to and can elicit soft contact.”

Whitmore’s parents, Mirasol and Scott, flew in on a redeye from Southern California to surprise her at her home debut, but she wasn’t in the lineup after going 0-for-2 with the HBP on Sunday at Gastonia. Alfonzo also used her as a pinch runner in the ninth inning of a game last week in Charleston.

“There was a little bit of chirping [from opposing fans] on the first road trip, but this weekend in Gastonia the fans were really supportive,” said Whitmore, whose teammates include two-time All-Star pitcher Julio Teheran and Kacy Clemens, one of Roger’s sons. “All of my teammates have been super-supportive. The clubhouse has been great. Right when I got here they all came up and shook my hand. And now they joke around with me, really like brothers.”

Whitmore has her baseball sisterhood now, too, something she didn’t get to draw inspiration from as a baseball player alongside the boys in San Diego before switching to softball in college. Since signing with the FerryHawks, she has received messages of support from Balkovec and many others, including one “really cool one” from pioneering former tennis star Billie Jean King.

“I know I would’ve been maybe less scared to go for it, but I didn’t really see much of it growing up, so I had to rely on how badly I wanted it to happen,” Whitmore said. “They’re paving their ways on the coaching side of things or in the front office, so I think it’s awesome what they’re doing, I appreciate their support.”

Coaching or front-office work is something Whitmore could pursue down the road, but she only is thinking right now about extending her playing career.

“That’s the goal, definitely, to continue playing the game as long as I possibly can,” she said, “and hopefully getting into a team’s minor league system and trying to move up like anyone else.”