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Some people are eager to invent useful things.
Literal
Convenient things [object-を] invent-[volitional-よう] [quotative-と] eager people [also-も] exist.
The volitional ~しよう plus quotative と expresses intent — 'people who intend to invent.' The と quotes internal motivation rather than speech. 熱心な functions as a な-adjective modifying 人. The も after 人 conveys 'there are also such people,' implying they exist among a diverse group.