Ecclesiastes 4:1 (Oppression in Qoheleth)-Is the Book Pessimistic?

"Then I looked again at all the acts of oppression which were being done under the sun. And behold I saw the tears of the oppressed and that they had no one to comfort them; and on the side of their oppressors was power, but they had no one to comfort them. So I congratulated the dead who are already dead more than the living who are still living. But better off than both of them is the one who has never existed, who has never seen the evil activity that is done under the sun" (Ecclesiastes 4:1-3 NASB).

For the record, I don't believe that Ecclesiastes is pessimistic, but here are some sources to consider:

https://academic.oup.com/jss/article-abstract/3/4/336/1655791?redirectedFrom=PDF

https://www.galaxie.com/article/bsac175-700-01

https://journals.co.za/doi/pdf/10.10520/AJA10109919_827

https://www.thegospelcoalition.org/themelios/article/ecclesiastes-in-context-reclaiming-qoheleths-canonical-authority/

https://scholar.csl.edu/ctm/vol22/iss1/2/

Barnes' Notes for Ecclesiastes 11:5

"As thou knowest not what is the way of the wind [ruach], nor how the bones do grow in the womb of her that is with child; even so thou knowest not the work of God who doeth all" (Ecclesiastes 11:5 ASV).

"Spirit - The same Hebrew word (like πνεῦμα pneuma in Greek and 'Spirit' in English) signifies both the wind-Ecclesiastes 11:4 and the Spirit (compare marginal reference). The Old Testament in many places recognizes the special operation of God Job 10:8-12; Psalm 139:13-16; Jeremiah 1:5, and distinctly of the Spirit of God Job 31:15 in the origination of every child. Compare Genesis 2:7" (Barnes' Notes on the Bible).

Disclaimer: I don't necessarily endorse Barnes' whole commentary on this verse.

Ecclesiastes 3:11-"eternity in their hearts"

What did Qoheleth mean when he wrote that God "put eternity" (הָעֹלָם֙) in the heart of man? And how does the last part of the verse connect with the preceding portion?

Robert Alter (The Hebrew Bible: A Translation): "Everything He has done aptly in its time. Eternity, too, He has put in their heart, without man’s grasping at all what it is God has done from beginning to end."

Alter's Footnote: "The Hebrew ʿolam means 'eternity' in the biblical language, though some interpreters argue that here it has the sense of 'world' that it carries in rabbinic Hebrew—that is, God has planted in the human heart the love of the world. It seems more likely that the intended meaning is: man is conscious of the idea of eternity (Qohelet as philosopher surely is), but that is the source of further frustration, for he is incapable of grasping 'what it is God has done from beginning to end.' Other interpreters reverse the second and third consonants of ʿolam to yield ʿamal, 'toil.' "

See also https://www.academia.edu/3770261/A_Reexamination_of_Eternity_in_Ecclesiastes_3_11