I hate metaphysics. I think it's a branch of philosophy that posits that there are 100,000 restaurants but never offers to take you to any one of them just to see what the food is tastes like. Metaphysics in this sense leads to salivation and leaves you hungry and empty. No menus and just positing the possibility of 100,000 menus. I like food so don't tease me with the idea and then leave me without being able to taste it. I've run into this kind of argument for the existence of a god or gods, in some supernatural sense. The argument hinges on a few things; that we as human beings are fallible and we do not know everything, a god of a metaphysical description is possible (the possibility is not impressive in any way), the ability to string a number of concepts within reality together, call it coherent and sound good while doing it. Usually the argument in a conversational setting runs like this; We know of many things and objects within reality but we do not know what is outside of reality. We have not been able to determine the cause of many or all things and we are still ignorant to our reality in many ways. We have not adequately explained the origins or the purpose(s) of life and we cannot rule out the possibility that a god exists.
Without qualifying which god they are speaking of or where they obtained this concept of a god, which they believe is far more than a concept (i.e. it's very real and has some significant role in our reality), let's look at the argument as it stands. We do know of many objects exist in reality as well as quantifiable phenomena. The odd part of some metaphysical claims is the claim about what is outside of reality. The claim is made within reality and the natural world as we understand it. What knowledge or evidence does the person have to claim that something outside of reality exists and/or has bearing on our reality and that thing outside of reality is "god"? Those are just statements used with the language we have developed over time to express a thought. The thought does not have any explanatory power within our reality. It's a load of hot air. The thought could be wrong, misinformed, held onto because it makes the author of it feel good and does not square with the facts on the ground.
There are things in our reality that may be unknown but that does not make them unknowable. We are still trying to gain an understanding as best we can, with the evidence we have in reality to explain our world/universe. The rest of the argument is an argument from ignorance/god of the gaps. It's a good way to demand absolute certainty with respect to knowledge about the world/universe (which we can't get nor need) and pitch an argument for the existence of a god, because of not possessing all knowledge of the natural world/universe, and place metaphysical statements about the god in gaps in understanding or knowledge. Not knowing a specific cause (one may not even exist at all or be necessary) does not give any credit to a god or gods being that cause. Even if the universe came into existence because of a FIRST cause, then all you have is a first cause. You have no reason or evidence to suggest or claim that the first cause is god.
The possibility aspect is an example of low standards for believing something as big as a claim about the existence of a god, whether the claim is metaphysical or not. Everything is possible under that standard. It's possible that in 10 seconds I will burst into flames and my entire home will burn down. You may think that sounds crazy but it IS possible is it not? If I adopt this weak standard of possibility, simply because I cannot rule it out, then how is the belief I have in me bursting into flames any more ridiculous that a god that exists outside of reality or caused reality into existence? It's possible that Santa Claus actually exists and so does the tooth fairy. It's possible that apples can vote within the next 10 years and chicken sandwiches can play football. Should we conduct our lives because of those possibilities? I don't think so. For the god claims to fly, metaphysical statements do not cut it. It's the epitome of verbal vapor without any explanatory power about our natural world/universe.
Life does not have to have a purpose in order for it to exist as it does. This includes all types of life which includes humans. That is not a bad thing. If you're worried about your life having a purpose, I think it is up to you to give your life purpose. We have no evidence to suggest a god, creator, or transcendent consciousness, or underlying intelligence exists at all. A lot of people have been very good at playing with words to express empty thoughts about our world. They play with emotional strings and some attempt to use science in such a way to support their claims but are later refuted by hard scientists. Most people do not see the refutations of the 'sciency' claims. They make appeals to us with shared experiences, usually through strife and unpleasantness to demand that something outside of reality must exist and in some cases, we are accountable to that thing i.e. god. Making statements about the existence of a god are merely assertions until proven otherwise. Insisting that the statements are true and have explanatory power are just more statements. Show me something other than words to prove that this god you speak of actually exists. Otherwise you are just blowing hot air.