Please officially confirm: a swarm (eg. swarm of ravens) is a single monster/combatant for purposes of targeting attacks, dealing damage, and adjudicating targets in areas of effect. Is that correct? Thank you for all you guys do. yes – if it's one stat block, it's one creature, though note that a swarm might have special abilities that interact with things like opportunity attacks
— Mike Mearls (@mikemearls) May 25, 2018
ok…if its one creature than why does the Monster Manual give a description of Tiny Beasts … it does not say Beast. Under certain spells it stats you target a creature or object or creatures or objects. singular and plural. under shapeshifting it stats you change into a beast. Under your logic above it would mean you can shapeshift into a swarm if it is a single creature….not a group of tiny creatures.