Mephis,
Yes, it is true that there were others who believed in Jesus, but did not follow the apostles per say.
Remember the texts that stated that others were casting out in Jesus's name, but did not follow the apostles ways. This does not mean that Jesus didn't start HIS church on the apostles. He commissioned the apostles to do ALL that he commanded. All other followers would not have the fullness of what Jesus taught. The bible came after the church. The bible was given to the world FROM the church.
There was a church in place by acts of the apostles. This is confirmed in the [1st] council of Jerusalem. Notice that James is the bishop of Jerusalem, but it is Peter who leads and controls the council. Jesus said to go and make disciples proclaiming the gospels to all the nations.
Ultimately, one must take everything into account. Is it possible that a man [or men] could decipher the scriptures better than the Church that gave them to the world? A church started by Christ himself? Perhaps that may be why you reason that Jesus didn't start a church in the face of explicit texts.