Please check my translation of a Japanese song (the original words in Japanese included)

Here is the lyrics of the theme song by スガシカオ in my favorite documentary TV program on NHK, "プロフェッショナル　仕事の流儀(Professional: How I Do My Job)"
I'm translating the first half of the song. Please review and correct. Thanks!

http://www.youtube.com/watch?v=cAdpzhIQQbU
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Stepping on the same mark, we all started off in a row.
ぼくらは位置について　横一列でスタートをきった

Seeing that guy stumbling, deep down, I was thinking it was great.
つまずいている　あいつのことを見て
本当はシメシメと思っていた

Forgiving someone and
Protecting my loved ones
誰かを許せたり　大切な人を守れたり

I haven't learned to do even a thing either of those.
いまだ何一つ　サマになっていやしない

Same as always, I'm no good, like on that day.
相変わらず　あの日のダメな　ぼく

My ideal self I've been always looking for was a bit cooler, but
ずっと探していた　理想の自分って
もうちょっとカッコよかったけれど

the days and the path I've been living seem to be actually called "myself"
僕が歩いてきた　日々と道のりを
ほんとは“ジブン”っていうらしい

世界中にあふれているため息と
君とぼくの甘酸っぱい挫折に捧ぐ…
It's This is dedicated to the sighs everywhere all around the world and the bitter sweet failures of mine and yours

“あと一歩だけ、前に　進もう”
"Let's move just one step forward"

I'm really impressed.  It is challenging to translate such things as lyrics, where the use of words can't be directly translated. Coming up with a suitable replacement of words and phrases in a non-native language, takes a strong knowledge of that language.  And I really think you did a great job, as I read both the Japanese and the English.

For me, going from English to Japanese is much harder than Japanese to English.  So I think it is great you took that challenge.

I'm going to offer some additional thoughts and ways I may have, personally translated it into English.

Stepping on the same mark, we all started off in a row.

ぼくらは位置について　横一列でスタートをきった

'In a row', is a bit ambiguous in English.  Often when we say 'in a row', we mean 'consecutively', or 'one after another'.  For example, "I won rock-paper-scissors three times in a row".  So in this translation, I can't tell if we were "in a row" side by side, or if we started "in a row", one after another.

Here's my translation:

We started off side by side from the same position.

Seeing that guy stumbling, deep down, I was thinking it was great. 
つまずいている　あいつのことを見て 
本当はシメシメと思っていた 

I really like how you came up with the phrase 'deep down', it's a good expression for this situation.  I think a good translation for シメシメと思う is "take pleasure in ~, deep down"

My translation:

Deep down, I really took pleasure in seeing that guy stumbling.

Forgiving someone and 
Protecting my loved ones 
誰かを許せたり　大切な人を守れたり

When I first read this, for some reason, I really wanted to know who that "someone" was.  But after noticing this was in the potential form, I think it flowed better in English as well.

Being able to forgive someone and protect [those|the one] I love,

I haven't learned to do either of those. 
いまだ何一つ　サマになっていやしない 

I would probably translate サマになっていやしない as the phrase 'less than perfect'.  Which means "I try, but I make a lot of mistakes"

I'm still less than perfect when it comes to either of those things.

My ideal self I've been always looking for was a bit cooler, but 
ずっと探していた　理想の自分って 
もうちょっとカッコよかったけれど 

Good translation on this.  Given the Japanese sentence, I couldn't come up with a better translation.  My only thought is that is using 'but' at the end of statement doesn't sound as natural as it does in Japanese.  To help the flow into the next statement here is what I would say in English.

Although, my ideal self that I've always been looking for was a bit cooler,

the days and the path I've been living seem to be actually called "myself" 
僕が歩いてきた　日々と道のりを 
ほんとは“ジブン”っていうらしい 

I actually struggled how this should be translated.  I think you did a good job on translating this sentence, but it still sounds a bit awkward in English.  I think ~っていう is very natural sounding Japanese, but 'called ~' is not used as much in English.  I'm still struggling on finding a good English translation to this but this is what I came up with.

my path in life, it seems, has actually just been a path of self.

Really good job on this translation.