There's always an explanation, though. The sun was in your eyes, so you couldn't see the ball very well. Or the wind picked up. These tennis balls also feel different. You also need another racket, which will help you hit the ball with better precision. You also need months of practice, but buying new equipment lets you feel committed to improving in this sport.
You may not play like Serena, but you should give yourself credit for getting better as a tennis player. Keep practicing, and challenge your friends. Playing with a friend adds to the fun, but you both should make something clear: this is a casual game. No ambitious shots, no overplaying; just hit the ball a little gentler, try to hit it back, and that's it. Until that questionable line call makes the game more challenging. You say, fine, take the point, but then the incident happens again. And then you're not playing gently anymore. You want to win. After the game, you'll remember that questionable match point for the next six weeks.
Doubles can be fun too. I don't know if many players like the experience of playing with a partner, but to me, the more, the merrier. As long as you can agree on who was supposed to hit the ball that just bounced between the two of you. Once you get a good rally going, the ball goes back and forth, and you're actually playing the sport you pictured when you booked the court. Afterward, everyone can grab something to eat and discuss the match. It's part of the experience and the fun of practicing a sport.
You can admit there's a gap between your game and Serena's while still enjoying your afternoon match with your friends. And you can celebrate a good shot like a big victory, because it really is. Besides, your friend saw that ball land perfectly and pretended they didn't, but you'll bring that up over lunch.