Answer :

Disease (The harsh winter that killed around half of the men)
Lack of organizational skill (ex. not having set Religious practices as they did in Britain, sending over only mean, not being well prepared in general)
Greed (especially in the gold industry)
Some ill relations with the Indians (although the first Thanksgiving was mostly peaceful, some problems arose)
I hoped I helped(: but I give you only 4
disease lack of skill greed sending mean people gold i think this is the answer:)