Buddha was a person some 2 000 years ago who found constantly happy life and great compassion from widened awareness. Buddha means enlightened. He and others with roughly the same insight founded the philosophy of life called Buddhism. Buddhism teaches the art of happiness and masterful skill coming from a natural wide awareness.
On western language buddhas found healthy happy life according to the human nature. A wide landscape like awareness is a part of that and gives wisdom and solves problems on the way. Healthy happy stimuli of healthy happy natural life according to feelings and with wisdom, give content to life and make one happy.
Even though not equally happy at all times but with variation from moment to moment, but with wisdom of life can one live with integrity also moments of sorrow and suffering which great skill and wisdom of life lessen noticeably, and so be continually almost happy or in a quite good mood and satisfied with life.