That's not what the text says. The text says David believes he will "go to him (his son.)" Not "follow him" or "mind-meld with him."
"Go to him." As in "being with him; joining him; seeing him again."
As in "At Thanksgiving, we go to Grandma's house for turkey." We're not in the vacinity of Grandma's house. We're sitting down next to her at the table.
Frankly from your description it sounds like you're a Buddhist, believing in one giant Happy Face from which we all spring and to which we all return. Very Platonic of you.
The fact you introduce doubt into this clear passage is troubling. Not for me, but obviously for you.
Phrase the question anyway you choose (just don't rewrite the text) -- Do you believe or was David correct to believe or are any of us correct to believe the David would "go to" (see again, be reunited with) his son again?
Or is heaven just another myth?
I said follow "in death." If you look up the Hebrew word "halak" its allegorical meaning, among others, is to die.
The Greek expression "poreusomai pros" (in Septuagint) has a nonsepcific meaning to journey at/nearby/to
Either way, the text expresses David's belief that he will "go" to/towards his son, literally or figuratively, wich is subjetc to interpretation.
Do I believe/know that he joined his son literally? I already told you: I don't know. I am not sure the Bible is clear on that. I know that the Bible says David believed he would. It doesn't say he did.
The fact you introduce doubt into this clear passage is troubling. Not for me, but obviously for you.
No need for toruble, the passage is not clear.
Or is heaven just another myth?
There was no heaven in Judaism of David's time, just Shoel. Post Babylonian (Messianic) Judaism speaks of Olam Ha-Ba (the World to Come) or Gan Eden (the Garden of Eden) as a place of spiritual reward for the righteous, butr doesn't go into any details.
Ancient and modern Judaism are very vague what afterlife entails, and allows for a variety of personal opinions, including reincarnation.
Because Judaism is silent on what afterlife is, the concept of (Christiab-like) heaven can also be believed by an Orthodox Jew.