AS is shown in the picture,we can see athlete has arrived to

第一句 see后面要加一个that arrive to要改成arrive at
AS is shown in the picture,we can see that athlete has arrived at the end
因为这是宾语从句 that是不能省略的 arrive at someplace 固定用法
the sign on the floor that is the start to only begin 这句话的语法有错误
按照楼主的意思应该改成the sign on the floor shows that it is just another beginning!
显然,他赢得比赛.然而,地上的标志标明着仅仅是另一个开始而已

arrived后面介词不能用to 用at 或in
we can see that
最后一句不明白

你这个怎么不通顺啊？原意是什么，我来帮你翻译诺。