Who is "we" in my thesis?

Solution 1:

It's a nosism (because weism is too close to bathroom humor), specifically the author's we.

Similar to the editorial "we", pluralis modestiae is the practice common in mathematical and scientific literature of referring to a generic third person by we (instead of the more common one or the informal you).

Solution 2:

In technical or scholarly writing, the universal "we" implies more than one person was or is involved with the project, experiment, or paper. There's always the Royal "we," in which monarchs always refer to themselves as a group. You can use "we" to infer that you're working with a group. However, it is always best to be forthcoming, and there's nothing negative about referring to yourself in the first person: "I."

Solution 3:

Apart from the typical explanation given in other answers, it is considered that in most cases, a thesis is a work of one or more students supervised by one (or more) academic instructor(s).

Now, even if you did your thesis without other collaborators, wouldn't it be at least arrogant and egoistic to not consider your supervisor in mentions and say "I" instead of "we"?

As in the end more than one people were involved in the thesis (even in different roles), "we" is the most logical and appropriate mentioning way.