Correct. It seems as if what happens in the universe happens largely by chance. Events are constrained to some extent, but there is no obvious teleology at work. You find this thought strange.
You do not appear to understand what an ad hominem is. Your grasp (and my grasp) of evolutionary theory are pertinent to the arguments we bring to this discussion. Your grasp appears, demonstrably, to be significantly weak in some relevant areas. Making that observation is not ad hominem.
Suppose you had been arrested for shoplifting and I brought that up as evidence that your views here were flawed. That would be an ad hominem. That's not what is happening.
We are only speaking about it so much because you are not willing to acknowledge that your grasp of the topic may be deficient in ways important to the discussion. Or, to offer evidence that we have misunderstood the extent of your knowledge.
I suggested you might find the idea you refer to "unattractive, disheartening and a little frightening". I find it interesting that of those three characteristics you chose the last one, placed there because it is the least significant, an insignificance that is emphasised by the adjective "little". Then, in what looks like an act of transference, you suggest I might be the one who is fearful. Not frightened, a lesser condition, but fearful.
Yes, that is definitely interesting. I ask you to reflect on it honestly.
Because that ability, to recognise there is no pre-existent purpose, coupled with the ability to decide upon purposes is much more interesting than merely eating, sleeping, breeding and occassionally farting.
It is not obligatory, but it makes use of many human attributes, some of which are said to distinguish us from at least some of the other animals on the planet.
It is hardly guessing. There is no meaningful evidence for a pre-existent purpose other than wishful thinking. Since my chosen purpose is to learn what I can of the universe during my brief incarnation and to help others to do so, then if there actually is a hidden purpose those efforts to learn may eventually reveal that secret to humans or their descendants in a thousand years, a million, or a billion. Not really very long to wait in comparison with eternity.
I have no idea what such an individual would think. Happiness is a rather over-rated state that simply indicates that ones lower
Maslow needs have been satisfied. In that respect the desire to feel happy is a good survival trait since it encourages action that are likely to preserve the individual and encourage procreation. Those are not, in my view, sufficient grounds from which to construct a purpose.
In summary, your responses still create the impression of someone who favours there being a purpose to life because you find it impossible/improbable that there could not be one. That an Argument from Incredulity and simply doesn't wash. You have'nt come up with anything else to justify your belief that there is a purpose. The onus is on you to do that.