is a common structure in Japanese used for indicating that something is ‘no more than (A)’, or ‘merely (A)’. This expression is constructed from に, and the negated form of the る-Verb 過（す）ぎる, meaning ‘to exceed’, or ‘to be more than’. Due to this, the literal translation of ‘to not be more than (A)’ reflects the English interpretations closely.
is slightly formal, but is heard fairly often in day-to-day speech as well. This grammar pattern may be used after verbs in any of their standard forms, い-Adjectives, な-Adjectives, or nouns.
I helped you just because I wanted money.
No matter how much you study, if you don't focus on your studies properly, you are just wasting your time.
That building is nothing more than old.
Tanaka-san is nothing more than handsome.
Fujita-san, you are nothing more than a child.
is often seen paired with structures that will emphasize the phrase even further, such as ただ ‘merely’ or だけ ‘just’. In the case of だけ, it will come between the target word and にすぎない. Also, standard conjugation rules will need to be remembered, such as adding な after a な-Adjective before だけ.
Fun-fact - にすぎない
may occasionally appear in set phrases, such as 氷山（ひょうざん）の一角（いっかく）にすぎない
, which means ‘to merely be the tip of the iceberg’.