It's true some people are born with perfect pitch. There are different schools of thought on whether you can truly develop perfect pitch if you weren't born with it.
There are different schools of thought on everything in life... choose one and follow through!
The first trick is: don't think perfect pitch is out of your reach. You can catch the curve and hang on. There is a curve in sound. Think about a train whistle or a police siren as they move.
When someone throws a baseball, it doesn't travel in a straight line. It's got a curve to it. It starts in one hand and moves through the air and ends abruptly at the bat, or in someone else's hand. Pretend we're watching a movie. Imagine the journey of that ball through the air in slow motion, complete with sound. As the ball is in the hand, it's silent. It's leaving the hand, and we start to hear the sound of the ball moving through the air, a low swish, getting higher as the ball picks up speed. We hear several tones within one sound. One is the wind moving around the ball. One is the ball moving through the wind. One is changing with the speed of the ball. And one is the abrupt stop of the sound, with the crack of the bat against it. (Or the thump as it hits someone's glove).
Are you with me so far? You might have to work at this - and thought - hmmm... stretch of the imagination. Yes, it is. That's good!
Stretching your imagination in this way is a good habit to get into. Stop right now and listen to the sounds around you. For me, at this moment, I can hear the ceiling fan. That, in itself, has more than one tone. I can hear the mechanical part turning, and the air being pushed from the blades, and a little squeak. There is the ticking of a clock. A car is driving by. My attention returns to the ceiling fan. I begin to hear a predominant hum. It's a tone. It's a note! If I keep listening long enough I could go over to the piano (or any instrument) and find the closest note. I'll try a B flat. Many things with motors are in B flat.
When you get into the habit of hearing everything around you as something musical, you are on your way.
Try this for at least a week. Do it on a regular basis! I find it improves my whole outlook on life. Come back and there'll be more for you on the process of developing your ear.