There is nothing in Q about Jesus not performing miracles. In fact many of the sayings in Q suggest he was just that kind of person.The Jesus of Q is not a messiah. He was not born of a virgin. He did not perform miracles. He did not die on the cross. There was no resurrection. What remains nonetheless is an extraordinary character -- the basic radical elements -- and an intriguing figure who made a lasting impression on his followers, believed in an immediate Kingdom, and saw himself as a successor to John the Baptist. The gospel may contain embellishments -- embellishments designed to bolster the fortunes of a struggling movement during an extraordinarily competitive period. Embellishments and obvious contradictions notwithstanding, the three synoptic gospels, Matthew, Luke and Mark, do agree in essentials and do paint a rather consistent portrait of Christ. There are elements in the stories that would not have been fabricated for a completely mythological figure; the flight after Jesus arrest; Peter's denial; Christ's inability to work miracles in Galilee; his early uncertainty as to his mission; his confessions to ignorance of the future; his moments of bitterness; his cry on the cross. It stretches the imagination that so appealing a figure could be created by a few simple men in a single generation.
Some of the embellishments in the gospels must be seen in the light of the times. It was a time when Jews were waiting anxiously for a Redeemer. It was a time too when magic, witchcraft, demons, angels, possessions and exorcisms were generally taken for granted -- as were miracles, prophesies, divinations and astrology. In that context the miracles ascribed to Jesus, although wrongly interpreted, are not beyond belief -- water walking and bread making notwithstanding.
The contents of the teachings in Q do not point to an ordinary man, but to a more or less realised guru (spiritual master).
The embellishments as you call them are outside of Q, made by the authors of gMatthew, gLuke and gMark.
That those three gospels paint a rather consistent picture of Jesus other than the one that follows from Q is no surprise at all since aMatthew and aLuke based their story line entirely on gMark and just mixed in sayings taken from Q as an embellishment (thereby degrading and abusing the instructions in Q).
The spiritual instruction in Q is entirely tantric (practical), not religious (theoretical) and the powers that come with spiritual self-realisation include the ability to perform so-called miraculous deeds controlling the elements directly with the mind. Of course Jesus was not unique as such a guru and did not claim so either.
No great guru goes withouth demonstrating their spiritual powers to their followers.
What aMark and other gospel writers did was change the original tantric Jesus into a religious icon to be worshipped instead of followed and loved.