Switch of distribution during observation period (Scratch Assay)

Dear Stats-Talkers,

I performed several Scratch Assays (its an experiment where cells close a cell-free gap over time, see also attached file I) but I stumbled into some problems during the analysis.

The cells were seeded in two different groups (treated and untreated = control). Now I want to know if the gap closing potential of the treated cells is significantly faster than the behavior of the untreated cells.

First I performed a two-tailed student t-test and I was pretty happy about the results, but then! I remembered my statistics lecturer. Student t-test is just for normal distributed data.

Second stage of statistic escalation: I tested every single group via Shapiro Wilk if it is normal distributed: e.g. (attached file II) and it happened that way it had to, some of my groups dont show a normal distribution. (Actually i guess thats a problem because of a small n (7 or 6 measurments) but well, now I dont know how to handle that.

Do I have to analyze the data of the same experiment with different statistical tests? (e.g. attached file III).

What do I have to do, if there is a normal distribution of data at time point 8h for untreated cells but the data of the treated cells are not normally distributed?

Well, hopefully there is some help out there. ^^
If I ask stupid questions I am sorry for that but I guess its a lack of experience xD

Have a really nice tuesday!

Data shown in attached file IV (percentage of gap-closure)