How do we define progress?
By the quality of life, where quality is subjective and people judge their own life quality. With this I mean the value that people assign to being alive. This is not in the encyclopedia that @ChristopherE links (very interesting, BTW) but probably we could classify it as a pragmatic (and possibly utilitarian) approach, there are probably authors that have elaborated on this better and more extensively that I would be able in a dozen of lifetimes, but if you are interested I could elaborate more.
Before you ask, no matter if you measure the global quality as the average or the absolute values, in both cases basically we are going to see that people think there has been some progress.
This could be an illusion, so this doesn't really answer the question, but it helps, as we will see.
Have we really progressing at all or are we in a constant state of
ignorance that we will never be able to escape?
According to previous definition, the beginning of the escape would be reaching immortality. A constant quality during more time makes a greater integral.
Therefore, in the creation of the previous perception (subjective and therefore possibly an illusion), we have objective factors that influence it, for instance life expectancy, health, leisure options, freedom of speech and all kinds of freedom, etc.
The point is that we have a perception of progress, but that perception is falsifiable because it has implications on objective data, and it hasn't been falsified yet, so it looks like a somewhat reliable hypothesis.
Moreover, we can falsify your assertion:
Do we all not think our age as the height of civilised world?
Not really, many of us think that our age is good when compared with the past, but the future should be better and that we should make it better. Also we have expectations, and we are disappointed by some of the outcomes, therefore (in short) the present is not perfect. I don't know about you, but I don't like people dying, I don't like that at all, and I think that could be solved in a few centuries (from 2 to 5), depending on interest and investment.
Basically we have an hypothesis that seems quite plausible. But we can go even further.
This progress, real or not, looks good and feels good, therefore it should continue. This progress, real or not, is also consistent with the objective observations that are related.
Therefore, from the pragmatic point of view (and in a functionalist fashion) we can say, "does it matter?". If we have an A, and another A that is completely and absolutely indistinguishable from the former A, can't we just say they are the same thing? I'd say yes, but this takes us to different philosophical problems.
To sum up, if it looks like progress, feels like progress, has the same effects that we would expect from progress and relates with observable phenomena as progress then we should be able to call it a duck, I mean, progress.