・・・、、。
A thesis? What I write is just personal essays, essay-like stuff, you know.
Literal
Thesis [dismissive-なんて]... I [subject-が] writing [topic-は], just musings, essay-like thing [copula-ですよ].
~なんて dismisses the previous speaker's characterization ('a thesis, of all things'). 随想 (ずいそう) is 'random thoughts, personal essays' — a somewhat literary term for informal prose. ~みたいなもん is casual ~みたいなもの ('something like'), with もの contracted to もん. The speaker is self-deprecating about their writing, a very Japanese social move — downplaying one's own work. The ellipsis after なんて marks the pause of disbelief.