Perhaps there've been older stone-carved writings found.
Stating "non-ballpoint" might be technically true, but it implies that you're saying that older ballpoint-based writing instruments have been found that you wish to exclude, or that there's something unusual about non-ballpoint writing instruments.
Stating "non-ballpoint" might be technically true, but it implies that you're saying that older ballpoint-based writing instruments have been found that you wish to exclude, or that there's something unusual about non-ballpoint writing instruments.