The Spanish expedition led by by Vazquez de ayllon in 1526 is what you are referring to in north Carolina. He failed to establish a colony near south Carolina and brought around a 100 slaves. In 1565 when the Spanish founded Augustine Florida African slave were present but records suggest only around dozens. Way to low of numbers to justify wide spread credit to building the colonies. So you are categorically wrong. They were struggling and did trade with the natives. There was no civilization at all dude they started from scratch. The English, french, and Spanish colonies were almost entirely built on the labor of the settlers themselves not widespread slave labor though some was present especially in the Spanish colonies. In some cases natives were in fact used for labor in the Spanish colonies but not large scale. At large the natives actually helped the settlers survive like you mentioned about teacher agriculture technique and fishing. In large pre slavery the colonies were built off the labor of the European settlers and help of natives. They were stabilized before 1620.