Paul then introduces the theme of the ritual of the Lord’s Supper by reminding the Corinthians that this was given to him directly by Jesus
I think this is putting words into Paul's mouth.
Per Meyer's NT Commentary and G.E Ladd's Revelation and Tradition in Paul, Paul uses a preposition here that is more closely associated with an indirect source instead of a direct.
Furthermore, it would be strange for this to be a direct revelation and for Paul not to specify as such. Note in Galatians 1 and 2 Corinthians 12, Paul does explicitly say that he received something from Jesus in a vision or a revelation. Why would he do that there, but here not say that explicitly?
From Maurice Casey, Jesus: Evidence and Argument or Mythicist Myths pp 180-181, it was normal to cite a tradition as originating from the fountainhead of it. If Paul believed Jesus was the originator of this tradition, it would be normal for him to specify Jesus, or "The Lord" as the origination. Quoting here,
He claims to have received the tradition apo tou kurio, thereby naming the fountainhead of the tradition, in accordance with the normal Jewish custom.
Casey goes on to illuminate several examples. Craig Keener in The Historical Jesus of the Gospels gives examples too in Chapter 20, "The Last Supper."
Finally, Joachim Jeremias notes in The Eucharistic Words of Jesus page 101-104 that 1 Corinthians 11:23-25 contains 9 instances of word usage foreign to Paul and idiom usage foreign to Paul, indicating that this passage is pre-Pauline. See the second link below.
Between
1.) Paul not specifying this is a vision or a revelation (like how he does in Galatians 1:11-12 and 2 Corinthians 12:1)
2.) Paul using apo instead of para to indicate "The Lord" as the indirect/ultimate source instead of immediate, which was common in Jewish custom per Casey and Keener.
3.) Paul's language here being that associated with passing on traditions (the received and delivered pair as Jeremias points out.)
4.) And, most importantly, the fact that this passage contains 9 instances of vocabulary and one instance of an idiom that are foreign to Paul. Why would he not describe a vision/revelation in his own terms?
There should be no doubt that Paul is indicating this is a tradition he is passing onward.
One could certainly still believe regardless that Paul did get this in a vision or a revelation, but there is a lot of evidence pointing away from that, and no evidence pointing towards it. If you think is a vision/revelation, it's a real head scratcher why this is the only Paul does not explicitly identify as so, and that he indicates the lord as an indirect source, and that while writing this, and only this, revelation or vision he all of a sudden heavily deviated from his own language/style. There doesn't seem to be any reason to think this is some kind of vision or revelation, and a lot of reasons to think Paul is passing on some tradition.