In keeping with the well written opinion above, I would say no, life/humanity is not the product of one or more accidents, as I believe you to be using the term. The last century or so of scientic inquiry and discovery has taught humanity that there is a certain probability to an event or events happening given enough time. It is this principal alone in our universe, under its physical constraints, that has resulted in self replicating organic molecules, ie, you and I. In other words, life is pretty much inevitable, and actually likely quite rampant amongst the stars.
This is both a loaded question and one that is unanswerable. First of all, nobody can answer for "all atheists" since, unlike organized religions atheists have no "doctrine" that all agree with. By definition, atheism means the absence of a belief in deities. Beyond that, there is a wide range of things about which some atheists may disagree with other atheists.
Second, does the question ask if atheists think ('believe') that each individual is the result of accident, or humanity as a whole species is the result of accident?
What is meant by the term 'accident'? If it means 'absence of intent' then I think most atheists would agree with that thesis. If by 'accident' you mean completely random actions with no rules or other principles of organization, then I doubt that anyone would agree with that. There are principles and laws of physics that tend to remove absolute randomness from most interactions among particles and energy sources.
Atheists do not believe that 'we' are the result of intentional direction or control by a deity. Beyond that, there is a variety of thoughts and concepts about evolution and so forth. Many atheists would answetr the question with a simple "I don't know"
Within the heart of every atheist is a set of beliefs about the world and nature and origin. While the term atheist refers to someone who does not believe in a deity, saying that "all" atheists believe the same way would be to turn atheism into a dogmatic belief system with rules, hierarchy, and officials.
- Your question isn't set out the way you probably think it is... Especially since this opinion poll is in a "yes" or "no" format. Firstly, no one could say "yes" that all atheists believe that they are a result of a "mere accident". Which only leaves a simple "no".
Secondly, the question of whether human life itself has any inherent purpose, does not necessarily follow from your question. You need to change the wording there and define what you're really asking for the poll.
Lastly, you seem to undervalue the concept of chance. Since chance is involved in all areas of life. All good things and bad things have involved chance. Probability or improbability. Chance is not synonymous with improbable, and therefore also does not suggest "random". We can not stipulate that something is random if we do not fully understand the event that took place. (Also see the Average Principle.)
Saying "mere chance" is very much an underestimation of what chance means, in everything that exists and how it operates - including the meanings we adopt in human life.
However, you might want to check out - Youtube-
The Great God Debate 2 - Dr. Sam Harris vs Dr. Craig
Sam Harris in this debate, discusses the origins of Objective moral values and the inherent principles that constitute a sense of human purpose.