The question of Paul's knowledge and his lack of use of the stories and sayings of Jesus is not the only ingredient in discussion of Paul's relationship to Jesus. There is also the question of the conflicting salvation messages of Jesus and Paul. Paul could have made extensive and explicit use of Jesus' teaching and yet he chose not to. The end result is that Paul ends up with a theology having a very different feel and emphasis from the religious belief system of Jesus. Over the years of my Pastorate as well as my years teaching on the Internet it never ceases to amaze me that when the different and conflict "gospels" and salvation messages of these two men are mentioned many respond that I must be wrong because Paul and Jesus taught the same things. Well of course their ethics and morality teachings are similar but again there are differences to be found between them. Such differences and contradictions prove that Paul was correcting Jesus as well as Biblical Judaism and I have a problem with that. The failure of many people and many Christian writers to notice such a difference between the conflicting salvation messages of these two men reveal their overall lack of understanding and comprehension of the Bible on the whole when addressing a book as thick and difficult as the New Testament let alone the Old Testament because, be not mistaken, Jesus' salvation message comes from the Law, the Prophets, and the Writings (Old Testament) as recorded as taught by him in the New Testament and Paul's salvation message is nowhere to be found in the Jewish Scriptures but only from pagan solar and astral worship and of course as recorded as taught by him in the New Testament. That fact coupled with the fact that Paul's writings came long before the Gospels shows his influence upon these writers as well as unbiased scholarship today can teach us, if we desire to listen, that the authors of the Gospels were not Jews and that they most likely were not written or credited to apostolic authorship until around 200 A.D. by Irenaeus.
Like I mentioned above it is taken for granted by many Christians that Jesus and Paul preached essentially the same gospel. However, it does not take a very sharp mind to observe that there are quite significant differences between Jesus and Paul gospels and messages of salvation.
There are differences in presentation, with Jesus speaking in pithy, pictorial sayings and Paul in sustained and often rather complicated arguments. But there are other differences, too: The center of Jesus' message is the kingdom of God; Paul, however, refers rather rarely to the kingdom, and it is not a central concept in his letters. The center of Paul's message has to do with the death and resurrection of Jesus, and he speaks of people being 'justified' rather than of 'entering the kingdom.' In many other ways Paul is distinct from Jesus: His massive interest in the Holy Spirit and in the Gentile mission, his negative attitude toward the OT law, and his teaching on the church as a 'body' all set Paul apart from Jesus (at least as Jesus is described in the synoptic Gospels).
Answer for yourself: What is to be made of this and other similar data?
One obvious possibility, fitting in with the observations we have already made about Paul's failure to draw much on Jesus' teaching, is that he was not trying to follow - let alone to reproduce slavishly - the ideas and teaching of the historical Jesus. Paul's theological vision arose rather out of his prior teaching of dying and rising godmen when growing up in Tarsus and his experience and vision of the risen Jesus in his own life, and in developing that vision under the guidance of the Spirit (as he believed) he departed significantly from the religion of Jesus, introducing new ideas and radically reshaping the Christian faith. Whether or not the provocative title 'founder of Christianity' is used, many scholars would accept the general assessment of Paul that it represents: He transformed the Jewish religion of Jesus into something very different, and he influenced subsequent Christian thought and belief decisively (David Wenham, Paul: Follower Of Jesus Or Founder Of Christianity, p. 7).
In order to answer the question "follower of Jesus or founder of Christianity'' we will need to weigh the similarities and differences between the teachings of these men as recorded for us both inside and outside the New Testament in order to see whether Paul and Jesus are at one in the main points of their theology and in the overall thrust of what they say, or whether there has been a major change of direction between Jesus and Paul.
So we have two disputed questions to consider:
The two questions are quite distinct, though not necessarily unrelated.