Your standards of success are unrealistic and don't reflect the history of spaceflight. Designing and building rockets is incredibly difficult and has always been marred by a high failure rate. The early years of the US space program had an abysmal mission failure rate. Vanguard (1957-1959) was a disaster with 9 failures out of 12 attempts. A 25% success rate. Ranger (1961–1965) had 6 failures in a row out of 9 missions. By Apollo the US cleaned up its act, but had multiple high-profile failures (Apollo 1, 6, and 13).
The Soviets were not better, the Luna program failed 11 missions in a row out of 12 missions. The N1 rocket went 0 for 4 and its failure ended the Soviet lunar program.
SpaceX Falcon 1 failed three of its first five launches, which nearly bankrupt the company. The rocket's successor, the Falcon 9, ended up becoming the most reliable rocket ever produced.
The fact that Starship even functions with so few test flights is an engineering marvel.
