Psalm 146:3 Do not put your trust in princes, in mortal men, who cannot save.
Job 25:6 "...how much less man, who is but a maggot-- a son of man, who is only a worm!"
A Skeptic has asked: Why are these verses not applied to Jesus, who used the title "Son of Man"?
For this topic generally, see here -- an understanding of the nature of the "son of man" phrase is required.
We may answer this first by noting that both of these cites proverbially stress the weakness of men: The Psalms verse by noting man's mortality versus God's power; the Job verse (which is incidentally a quote of Bildad the Shuhite, and therefore hardly to be used as authoritative in this context) by stressing man's inability and lack of power to justify himself before God.
Unless one is a docetist, one does not doubt that Jesus' human body had all of the normal frailties of a body of flesh. It is certainly no shame to apply the Psalms verse to Jesus, and Jesus actually serves as an "answer" to Bildad's question of how indeed a "worm" like a son of man can be justified with God.
These verses neither reflect the titular use of "son of man" by Jesus, nor do they compromise the power and dignity expressed in the other claims of Jesus.
But there is even more to this, and it has to do with the phrase "son of man" and how it was used in the ancient world. You can see more details in the linked article above, but for the present context, it is enough to note that Psalms and Job use a different word for 'man' -- the phrase drawn from Daniel, used by Jesus, was bar enash. Pslams and Job use bar 'adam. This is a very significant difference, as we show in the linked article.
Bottom line: These verses are not "intentionally ignored" because they "tarnish the image of Christianity's founder" as one Skeptic charges. They neither are ignored nor do they tarnish; they no more degrade Jesus than they degrade the "sons of men" who authored the passage; they do not represent a one-dimensional judgment of man's condition. The critic must do more than simply cite identical words in English; he must also show that the genre and context of the passages require application to Jesus in the way he suggests, and that their contextual meanings somehow would "tarnish" Christ.
As we show in the linked item above, the Daniel 7 Son of Man figure was specifically used by Jesus, as well as by other Jewish exegetes of the period who deciphered a Messianic figure from the phrase -- and apparently, especially because of the difference in Hebrew, saw the cites in Psalms and Job as no more relevant in the way the Skeptic suggests than we do here. Clearly, these cites did not carry any negative connotations for anyone assuming the title; and if they did, then we must also ask why Jesus (and other Jewish sects) would make use of it in the first place!