This is not true. Sure, he was one of a few and I say few that helped speed along the space industry but they were by no means the founders of the space industry.
Just so as you know he wasn't even the inventor of the jet rocket.
Goddard, Robert Hutchings, 1882-1945, American physicist and rocket expert, b. Worcester, Mass., grad. Worcester Polytechnic Institute (B.S., 1908), Ph.D. Clark Univ., 1911. From 1914 he was associated with Clark Univ., becoming a professor of physics in 1919. Goddard designed and built early high altitude rockets. In 1926 he completed and successfully fired the world's first liquid fuel rocket. He developed the first smokeless powder rocket, the first practical automatic steering device for rockets, and innumerable other rocket devices. He was one of the first to develop a general theory of rocket action and to prove experimentally the efficiency of rocket propulsion in a vacuum.
Von Braun was not alone. He was A founder and only one of many German scientists who came to the US for their work in rocketry and missiles. Huntsville Alabama, home of Redstone Arsenal, Missile Command (exact name?) has a relatively large German population now because of them.
We also had German nuclear scientists and many other types of physicists, ngineers and mathematicians come to the US.
The other half of the German scientific community went to the USSR.